In an experiment to measure the heat released by the combustion of a sample of nutrient, the compound was burned in a calorimeter and the temperature rose by 3 .22 ° C (the same as 3.22 K, because degrees Celsius are the same size as kel vins). When a current of 1.23 A from a 12.0 V sourceflows through a heater in the same calorimeter for 156 s, the temperature rose by 4.47 °c (which can be interpreted as 4.47 K). What is the heat output of the combustion reaction?

8. A heating element using nichrome connected to a 230 V supply draws an initial current of 3.2 A which settles after a few seconds to a steady value of 2.8 A. What is the steady temperature of the heating element if the room temperature is 27.0°C? Temperature coefficient of resistance of nichrome averaged over the temperature range involved is 1.70× 10 °C-1. -4

When an electric heater is turned on, the Nichrome heating element is at 0° C and draws a current of 14 A, with a potential difference of 120 V between the ends of the element. The element heats up to 744° C, with the potential difference constant. Find the final current. (The temperature coefficient of resistivity of Nichrome is 4.0  10-4 (°C)-1.)

A tungsten wire in a vacuum has length 26.0 cm and radius 6.00 mm. A potential difference is applied across it. (a) What is the resistance of the wire at 293 K? Ω (b) Suppose the wire reaches an equilibrium temperature such that it emits 70.0 W in the form of radiation. Neglecting absorption of any radiation from its environment, what is the temperature of the wire? (Note: e = 0.320 for tungsten.) K (c) What is the resistance of the wire at the temperature found in part (b)? Assume the temperature changes linearly over this temperature range. Ω. (d) What voltage drop is required across the wire? (e) Why are tungsten lightbulbs energetically inefficient as light sources?